ABB REC670 Product Manual page 10

Bay control REC670
Pre-configured
Product version: 1.1
CT circuit will mean that the situation will
remain and extremely high voltages will
stress the secondary circuit.
Current circuit supervision (CCSRDIF)
compares the residual current from a three
phase set of current transformer cores with
the neutral point current on a separate input
taken from another set of cores on the
current transformer.
A detection of a difference indicates a fault in
the circuit and is used as alarm or to block
protection functions expected to give
unwanted tripping.
Fuse failure supervision (RFUF)
Failures in the secondary circuits of the
voltage transformer can cause unwanted
operation of distance protection,
undervoltage protection, neutral point voltage
protection, energizing function (synchronism
check) etc. The fuse failure supervision
function prevents such unwanted operations.
There are three methods to detect fuse failures.
The method based on detection of zero
sequence voltage without any zero sequence
current. This is a useful principle in a directly
earthed system and can detect one or two
phase fuse failures.
The method based on detection of negative
sequence voltage without any negative
sequence current. This is a useful principle in
a non-directly earthed system and can detect
one or two phase fuse failures.
The method based on detection of du/dt-di/
dt where a change of the voltage is compared
to a change in the current. Only voltage
changes means a voltage transformer fault.
This principle can detect one, two or three
phase fuse failures.
Control
Synchronizing, synchrocheck and
energizing check SESRSYN
The Synchronizing function allows closing of
asynchronous networks at the correct
moment including the breaker closing time.
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1MRK 511 192-BEN B
The systems can thus be reconnected after an
autoreclose or manual closing, which
improves the network stability.
Synchrocheck, energizing check (SESRSYN)
function checks that the voltages on both
sides of the circuit breaker are in
synchronism, or with at least one side dead
to ensure that closing can be done safely.
SESRSYN function includes a built-in voltage
selection scheme for double bus and 1½
breaker or ring busbar arrangements.
Manual closing as well as automatic reclosing
can be checked by the function and can have
different settings.
For systems which are running asynchronous
a synchronizing function is provided. The
main purpose of the synchronizing function
is to provide controlled closing of circuit
breakers when two asynchronous systems are
going to be connected. It is used for slip
frequencies that are larger than those for
synchrocheck and lower than a set maximum
level for the synchronizing function.
Autorecloser SMBRREC
The autorecloser (SMBRREC) function
provides high-speed and/or delayed auto-
reclosing for single or multi-breaker
applications.
Up to five reclosing attempts can be
programmed. The first attempt can be single-,
two and/or three phase for single phase or
multi-phase faults respectively.
Multiple autoreclosing functions are provided
for multi-breaker arrangements. A priority
circuit allows one circuit breaker to close first
and the second will only close if the fault
proved to be transient.
Each autoreclosing function can be
configured to co-operate with a synchrocheck
function.
Apparatus control APC
The apparatus control is a function for
control and supervision of circuit breakers,
disconnectors and earthing switches within a
Issued: June 2010
ABB